Yo! Just a passing curiosity. Over the years, we have came across a number of memorable foes and fiends. So let me know who some of your favorites are. Go into as much detail as you want.

My top picks are (in no particular order):

Funny Valentine (JJBA: Steel Ball Run)
Misogi Kumagawa (Medaka Box)
Rob Lucci (One Piece)
Zeref (Fairy Tail)
Shishio Makoto (Rurouni Kenshin)

Hey we already have a thread for favorite anime villains, and while villain and antagonist aren't always the same thing these two threads have a pretty much identical purpose.

If yours would have been for anime & cartoons I would have probably supported it as a replacement.